Got my 750 kit installed

[XSLeo]

I got the last of the parts I needed to assemble the 750 kit on my 75 engine.
I rebuilt the crank a few weeks ago with new bearings and Mike's heavy duty rods. Got the lower end buttoned up last week. Today after the parts got here I assembled the top end. That 750 jugs and pistons are awesome. I got them installed, went very well. I used the 75 head I polished up some, the stock 75 cam. Before I put the rocker box on I took the elephant foot adjusters out and shortened them about 1/4 inch. I just left them full length when I first put them in.
I got it assembled enough to crank the engine over with the starter. I checked the compression, 220 lbs on the left, 230 on the right. It may settle down after it has run some.
I rode a 750 kitted bike. It was very impressive. I tried to kick start it. I couldn't quite get it to start. With a bit of practice I will probably be able too.
In case I can't I got the decompressor valve cover from an early bike. It will save my leg as well as the electric leg.
I just need to rig up a lever and cable to actuate it.
I bought Mike's 1.5 inch headpipes. I have two sets of mufflers I can use. The stock set and a set I took off my Harley, an '03 FXDX. To use the stock mufflers I will need to cut the headpipes off. They come back and turn up on the ends. About 6 or 8 inches too long.
The Harley mufflers will probably work without cutting the headpipes. I may run the Harley mufflers for a bit, I don't really like the way they look on a 650. I'll decide that later. Now I just need to get it into the frame and see if it runs.

 

[MB-Ian]

Sounds more or less exactly what I have on my B.

It's a bugger to kick start, no two ways about it. I've only succeeded a couple of times, best way seemed to be to kick it over twice with the kill switch on and both chokes on to get some petrol into the chambers, then turn the kill off and give it a hefty kick will start. How to do it when its warm is anyone's guess.

Having never ridden a standard XS650 I don't know if I'm missing anything or not, but the 750 is great.

I.

 

[bigpup]

xsleo, pics?

 

[TeeCat]

Leo, sounds like a neat setup! Glad to hear it's going well... anxious to see pics!

And that's some serious compression, yeah?! Wow!

I'm impressed, man! (And here I am up nights about my little ol' single carb conversion... You could probably get an old Amana refrigerator to run an 11-second quarter... )

 

[Visegrippe]

Basically, w/ my 750, the kick is quasi useless, i'vebent 2 kick levers already... though I finally got the electric start working properly.
Some times the comression alone was enough to lift me back u, and I'm 230lbs...

Sure does run nice as I slowly tune 'er up.

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[weekendrider]

Good on ya Leo.
I'm with you on the Harley exhaust unless you can route them to the same side.
Down each side looks to much like a Honda Rebel.

 

[pyrocentric]

Wow, I had no idea the 750's were that hard to kick. The easy kickstart is my favorite thing about the XS.

What's the compression ratio on that kit? I guess you could do the old XSJohn double headgasket trick to get it back down.

 

[XSLeo]

Mike's says the compression ratio is 9.1-1
I have read about a guy that ground the shaft where the kicker pedal arm mounts square and put a Harley kicker arm on it. They sell heavy duty forged kick arms that are longer than a stock Harley arm. I don't think you will bend one of those.
Once you mount a Harley arm they have dozens of pedals to put on them.

 

[Visegrippe]

Wiseco claims 10.5 to 1. Now that my advance has new springs it doesn't kick nearly as much. Still a work out to start it cold.

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[MB-Ian]

I'm just wondering whether mine is harder to kick due to the rephase? I'm thinking that on standard engine the compression strokes are 180 degrees apart, whereas on the rephase there are 2 compression strokes fairly close together and then a long period before compressions come around again... or wouldn't that matter too much?

I.

 

[XSLeo]

Actually a rephse may be easier. Kick it over slowly until you get to the long part of the cycle, bring it up on compression and kick it over, With the two compression strokes closer together you are kicking through both compressions higher on the kick stroke. Instead of one on the top and one most of the way down.
It seems like you would get less kickback and a smoother stroke.

 

[MB-Ian]

What carbs are you running? I'm so frustrated with my VM34s I'm tempted to install standard BS38 (is that what was being used in '75?) and shelve the VM34s until a later date when I can examine them jet-by-jet and fix the warm stall issue. They are also a pig to warm the bike up either on or off choke... I'd have thought with the bigger bore and raised CR the engine would warm up quicker but it takes ages and stalls over and over while putting on me gloves and the like.

I.

 

[XSLeo]

The carbs I'm using are a 76-77 linked set with the needle jet and needle from a 74. So I'm running pilots and mains that match the needle jet and needle.
They have been working good until just lately, They have developed an off idle stumble that I can't seem to cure. I have changed the jets, Put the needle clip in all five slots with no change.
I got the 750 engine in the bike and it runs very well. The off idle stumble is still there.
I shot some carb cleaner around the throttle shafts and the idle went up and smoothed out, so I guess I need some seals.
As far as the engine swap went, everything went very well. Got started about noon, pulled the 82 engine out of the 75. Slipped it back in the 82 frame. Rolled it out of the way.
Rolled the 75 engine over, put it in the 75. I left the clutch and side covers off to help reduce the weight I was picking up.
I then put the clutch together, Mike's new thrust bearing with a bunch more rollers in it. The Kibble White clutch springs. I modified a set of spring screws to use Allen heads instead of Phillips head. I put a new spring on the #3-#4 starter gears, engages right now, no hesitation.
I cleaned up a set of fiber plates with degreaser and 80 grit sand paper. I sanded just enough to remove the shine and rough them up a bit. The steel plates I used the 80 grit to remove the discolored spots, remove the sharp edge from the stamping process, and rough them up a bit.
Doing this to the plates and the new springs the clutch don't slip any more.
I used all six springs, I will try it later on with three new and three old springs. The lever pull is a bit stiffer, not as much as I expected.
I didn't hook the oil cooler in for now. I thought I would hook it up after break in.
At about 5:30 I was taking it for a test ride.
I used the stock exhaust for now, still undecided on what mufflers I want to use. I was looking on Ebay, JC Whitney, Mike's. I think I like the looks of the Dunstall style mufflers.
I like the Megaphone style to. Some of the slash cut mufflers look good too.
Ah decisions. The bike runs well. A few carb adjustments and new throttle shaft seals, along with the new headpipes and decent mufflers it will be even better.
I know people don't like the vibrations you get above 4000 rpm. I think you should find some one with the 750 kit installed. Take it for a ride, you will be amazed how smooth the 750 runs. This engine is just as smooth at 3000 rpm as it is a 6000 rpm. I had heard that the 750 kit smoothed out the vibes some. I can agree with that. Very nice.
As a 650 I was thinking of swapping the 30 rear sprocket for a 32. I had a 32 on before, I liked it. A bit less rpms at cruise yet still good accelleration. As a 750 I don't think I need to now. The extra power the 750 makes can handle the 17-30 just fine.
I'm still considering the different primary ratio gear set. These new primary gears will make the overall gear ratios much more usefull. I think it would make the bike almost perfect.